Floating dry dock



July 3, 1945- J. S. CRANDALI.

FLOATING DRY-'DOCK Filed Nov. 25, 1943 5 Sheets-Sheet 1 Aia/m A /70 lf2 205 476. /33 v135 jvan or:

July 3, 1945. J. s. CRANDALL FLOATING DRY DOCK Filed Nov. 25, 1943 5 Sheets-Sheet 2 *L r. w my M July 3, V1945. l J. sj-cRANDALL FLOATING- DRY DOCK Filed Nov. 25,4 1943 5 Sheets-Sheet 4 y venan I u I July 3, 1945. 4

J. `s.- CRANDALL. 2,379,685-

FLOATING DRY DOCK Filed Nov. 25, 1945 5 sheets-shed 5 J'nvenor.

` Patentedv July 3, 1945` o k2,'3'194135 `j o o o f FLoATrNG DRY lJooK` o o James Stuart Crandall, Lexington,` Mass., as-` i signor to Crandall Dry DockEngineerswInc., Cambridge," Mass., a corporationof Massachu- `ApplicationNovember 25, 1943, SerialNo." 511,713

15o1aims,.` o1.114`45) o Thisinvention relates to improvements in 4floatingr dry docks. o More particularly it relatestoya floating dry `dockhavinga bottom hollowsection and hollowwing sections risingvertically fromthe bottom section atleach side thereof between which and over the bottom section a` boatto `be dry dockedmay be'floated when the dry dock issubmerged. Ordinarily, the bottom diameter, the amount offpiping, heretofore necy essary, hasbeen considerable and asfmany as four direction-controlling valves Shave been `re `quired at each compartment; naddition to the flood gate valvefr` satisfactorycontrol of the I entering and departing Water. This `has involved section Vis divided centrally and longitudinally by an interior central bulkhead extendedfrom end `to end and longitudinallyjof the bottom section. `and transverse bulkheads extending from the lon-1 gitudinal bulkhead to .the sides of` and `into the wings of the dry dock provide; a, longitudinally o aligned seresfofwater"tightcompartments along each sideof the central bulkhead.` llacheomi` partment usually is provided Vwith ayfloody gate opening and valve therefor and each is equipped with means for pumping Water from `the `comv l partments `Whenthe `dry dock isl to be` elevated.

The amounts of water inthe various `compartmentsmay be different to adjust the buoyancy heavy expense for `the piping and -the valves and the valves have had to be operated by hand by men on the top ofthe Wings,` or` decks of the dock.

It `is an object of the" presentinvention to reduce greatly the amountn of piping required for each compartment and also `to eliminatethe direction-controlling valves and hencefto reduce versible-ilow pump is a propeller type pump and one, designed not to `become `unduly overloaded. "even thoughthe gate` or`;.shut1off valve in the of the` dock at such compartments to `thevveight of the parts of the boat oventhem.

Somevoating dry docks have a bottom section constituted of steel whilejothers areof Woodjconstructiom A `Wood constructionismore buoyant than asteel construction and `is sometimes bal- 'la'stedr to-.reduceits buoyancy. `With a'steel construction the heightof water in the `vvingsunay notbe higher than, or as high asjthe level of the .outside Water toobtain sufficient submergence of the dock to permit entrance` thereto of the boat of deepest draftthe docktis designedzto receive.

With a'wood dock, unless permanent ballast is" used, the water inthe Wings maybe higher than the outside water level for maximum docksubmergence.4 `With a steel construction,'inabsence `of `a sealed airchamberwhich sometimes is provided inthe lower body" of a steel dock,`thej tendency` for gravitational Water flowalwaysis into the dock `While with a Wood construction the flow canbe in eitherfdirection depending upon the `degree of submergence of; the dock.My inven- 1 tion is usefulfwithdockls of either Wood or steel [construction but is `particularly useful in'connec tion with docks of vvoodconstruction.` y

Heretofore, centrifugal lor .o other, uni-directional-flowpumps have beenlemployedfor'lling and `exhausting the Water compartments and a syswaterentering and leaving the. dry `dock with control valves for changing the direction ofow of thewater. l Inasmuch as these pipes are necessarily lof large size, such as `10 inches or more in' 5o tem `of piping has provided for controlof the the number-of valves necessary at each com` partment by the `use of areverlsible-ow pump and a reversible driving `motor `tlrierefor sof that water-can be pumped into or outof thedock compartment by rotating the pump and motor in either one or the opposite direction.` o o o Another object of the invention is ,that the repipin'g between the dockcompartmert and the outside should close on the operating pump. f

` In. pumping-up or elevatinga" [steel dock' and, usually,y in both pumping down tand pumping up a wooden dock there is, at the end of thepumping operation, fa hydrostaticfhead `of water tending-` to cause water to flow throughthe pumpin the opposite direction to the direction of flow `during thegpumping operation if the shutfof Ivalve in thepumpfline is not closed promptly at the end of the pumping operation; It isnot always `practicable to close `gtlrie "manuallyoperated valve.` promptly so that `the Water` level can changeand the `level must be restoredby another pumping operation until the valvevcan'be closed. `The reverse flow ofthe `Water rotates thepump impeller and1 motor reversely `by"t`l`11b`l1i?"` action `and the motormust reverse the direction of' rotationjof the spinning parts. `This imposes aconsderable` l goverloadjon themotor` and its circuit and strainV on the impeller and its long shaft connection with` ',"It is an"object"offthfprsent invention to preventmthe` otatfionoffthe pump `impeller when the motor is defenergize'd and particularly 'to provide fori. the purpose` means automatically responsive to` the energization and deenergization of Ithe driving motor...

It is particularlyan ebiect offthis invention `to provide a `valvefin the pumplinethat `will close l automatically whenlthelpump ceases `tobe driven positively by the motor, thereby to shut off water l v getest gravitational now. of water thereinto'. A wood dock usually-sinks onlya certain amount less than full'submergence,` at which time thewater is at about a common level under/and outside the dock and the gateaislthen closed and water is pumped into the dockto elevate the water level therein above tneoutsidlevei tosink the deckte its fun extent. Thepumps alsol exhaust the water from Ahe.compartments"with the iiood gate closed'to pumpup orelevatethedcck. 'a y L `It".is common `alsoto` provide ernergency'flood gate openings at 2B, Figs.3,` 10` and `11`*,o`pe`ning through the transverse bulkheads 2i]l between "the compartments to noodand empty one compartment from Van adjacent one, upon need, the gate` opening being controlled by agate 21,.,vertically movable by a shaft28operated through a lever 29 by a vertically movable shaftoperated from the' top of the dock wing:

`Instead of lpumpingwatenby uni-directional flow pumpsand using valves to control the direction 'of flow of the water into and lout of -the compartments, the pump Aof the present invention,

andhasbearingsl, ""II onfopposite ends thereof. The upper end ofthe casingalso hasan annular exterior flange 84" to whicha coactingjflangeA 86 on elbow 38 maybe secured as bythe `bolts `381] A `bossgfon thelouter curved wallet thaelbow 38` f `is-apertured for reception of they lwferreduced end of an interiorly threaded sleeve 592within is screwedtme end of a'lcinglersleeve` 94 whose lower end` is threade'dly :engaged withkthe a 'sleeve 80. This long sleeve 94f`constitu`tes `a -xed tubular protective 'I casing extending vertically acrossthe flow passage of elbow 38, and thepu'mp a a a a is Amade in two lasections, the lower section of wl'iichterminates a little above the elbow 38. The upper 1 end ofthe lower section `of shafttand thelower en'd of the upper section `of shaftiare joined together `by coupling member 96, the joint being protectively encased as at 98, and the upper sec-1 r tionof shaft being encasedlasiatlll. L. w

l i l" The `driving moto`r`36 for the pump `islocated for each compartment, is a reversibleeow pump 34op`erated by a reversible electric motor 36, Figs, 3,'4 and 81. lI'he `pump is `verticallydisposed and l the` upper open endof the casing thereof is con- I nected to thelower end of an elbow 38, the other endof which is connected to a shorthorizontal conduit 40,` that opens to the outside water through the side or skin of the dock section, the opening 4preferably being covered bya grating` 42. The gate valve 44 is interposed in the conduit between the pump and the outside'conduit-opening and is operated by avertical shaft liand` a hand wheel 48` above the deck of the wing; `An`auto.

matically-operated valve casing 49 is also interposedinthe conduit between the pump and the gate valve and contains a buttery valve 50 fixed to a shaft 5I`andjo`urna`lled in the casing 49 and 'V operated by mechanism hereinafter "to be described so that the valve is open when the pump motor is energized andis closed when the motor is de-energiaed.4

The particular 'type of reversible pump illus` trated in enlarged detail in Fig.` 8 has a casing `body 52 having aybell shaped entrance anddis-` charge opening 54 at"` its `loweriend terminated `on the wngdeck,` above the purnp,tandfis` connected to theupper end of the pump shaft 59. I.The l motor is reversible as toits `direction ofrotation a three phase `alternating cur;- a

'and preferably is rent motor. i

I While Ithave `herein describedl a particular construction of reversible now pumpwhichl find satisfactory, reversible flowpumpslofiother de- 0 sign may be employed within.thelscopeof` this invention. a l l .l

As shown in y located lowdown in its compartment, being -vertically disposed therein, with its openmouthclose a a to the bottom wall of the dry dock so that `water in the Vcompartment may vbe sucked into` the` l pump and driven through thefconduitout to the' the pump is operated inone direc`` exteriorwhen non. r r a .a .H

Unless provision @is -made` for preventingcit,

there may be times during theoperationof the dock with .the pump conduit openfwhenwater caniiow through the idle pump and rotate vit as `a turbinelat the time the pump isstarted upfinl a direction to reverse the water flow. Applying driving power in a reverse direction on the motor of the spinning water-driven'pump results in an above the bottom wall I4 and within which bell is a "axially mounted onl radialribs `56 *a bearing 58 for the lower`end of thepu'mpshaft 59. l Provision isfmade` as at `6I) for suitably supplyingthe bearing withlubricant.

lThe pump` propeller r'impeller 6l is `xed on radial blades `621are of shape and pitch to propel response toopposite directions of rotation of the impeller. Alsothe pump is so designed,-in"a`wel1 `shaft 59 closeabve the bearing'58. `Its generally `water infopposite directions through the pump in :shoum rbe closed against 'outflow winne the p/ump n `continues in operation, thereby permittingfclosing of "thegate valves at `will` prior toqshutting interior 'a annular `walls 68 which curvefoutward excluded 4from.` the. ow `passage of the pump; and thedrive 'shaft 59 extends through" this space e upper portion of the pump casing body has being a with energization of thepurnpmotor. The valve l `is so arranged that it automatically `assumes overloading of the motor andthe impositionfof ,undesired stresses on the drive lvshaftv andi-the pump impeller. l To prevent such `overloading and over-stressing of the parts of the pumping system means preferably is provided .to `prevent Y `the pump from rotating .except when the motor is energized. To; this end use is madeoflthe heretofore describedbutterfly 'valve 50, said valve self closing and beinglopened automatically closed position, as shown, asfor instancawby l,being balanced `against waterrpressureracting thereon and being overbalanced in a closing` di- H rection bythe weightV of the operating linkages connected therewith; land also is caused to open in response to operation of the pump. For` this latter purpose anelectro-magnetic Valve-operating device 296 is provided `including :a motor 201, the two terminalsof the magnetizinginotor winding of which are connected through two leads 293 with two 'separate .terminals of l the pump motor 36 or to the "conductors leading therefrom to a starting switch |30 for the `pump motor. `.This latter motor 36 can be a three phase motor as it: drives a pump impeller whichcan Fig. 3, each ofthewpurnps `i4 is tively.y Such motor201,`when energized,A operates .itsoarniature or irotor. to., operate ai pump that creates. fluid. pressure.- Qn v.a piston yin thescasing 2I0 totraise` thepistoncrods v2 I-2aagainstf ay lever v2 I 3 `pivoted at one .endl -on Ithe'.fixed'.lzrracket`..2 I 4 and Aconnectedat its othenend. with `a'f-vertical pullrod'ZIBrpivoted .at-.its lower/end tothe end of an armtZIB-xed to thevalve 50.4 The arrange- -mentissuch that thevalve is .moveditrom closed to openA position concurrently .withthe energize.- tion. of..v the pump motor -t and retains this open position; 'during fthe 4operation of. the motor. and pump and closesfbecauseof :theweight vofthe rod 4-2 I6 `:and associated parts uponf-fme` cle-ener- Agizatiorr-jof tha-motor.. A 'The' motor .-2 011 `preferably rotatesin the same` direction.-v irrespectively o f reversal of.v fenergization off the ,preferably ythree .phasefpump motor so that the valve 50 `is opened veach time: the. pump is .operated; .regardless of the direction@ of-rotation. .l Thus f. watereiiows through the pumponly when the `pump is -oper- .ating landdanger- `of 4injury to :the motor. and pump and Aconnections therebetween is obviated. :The buttery valve,y where wused, eliminates-the .necessity .for running@ the pumps.; after the dock has beenfully:` elevated vand until the fgate .valves 44 can be closed and hence is convenient although iisd-ces :'not. eliminate.. thefgatenvalve'f since'r :the lbutteryvalve, byvreason' offits nature-, can-not ben completely.' water. tight' 'and'. .hence the' ngate .wah/elias .toi'beiclosedfultimately. s

The boat is chocked to `hold it verticalwwhen rit `:rests .onlibe-dicen oit-the doch` :1 Anyfsuitable chockingimeans may :be provided y on r.the rbottom fsection' .ofzzthe 'dryi dock. I have illustrated .in

aarfaess common to al1 thev .motors on the .same Wingateinsl duplicated .ih theiotherwingslas indicated at '1I 33a, and 'both connectedtogether. prior tojpass; i-ngthrough the .reversing sw'itcl'1 "|3'4 so 'th' motors, on. both wings, `are conditioned j alllfor forwardfdriveor; all for reverse drive,j,dep`ending -upoirthev setting ,-o'f. .the reverse switch'. Thermo..- torlcontrol switches I 30 and thefreversing i switch are, hereinldiagramrnaticallyf.illustrated,and can be of different constructions and`;hence are, not

` intended to.illustrateany.particular construction being. .illustrative Lonly. .,'Asherei illustrateithe.

conductorscontrolling .the opening and ,closing of the .control switches -.I 30. and herein speciically Vthe conductors `connected .the electro-I nagr trolhouse `B Abeing :provided eachJfor gthercoltrol ofauseparateffwing Aof .the dryjdock, one: otjwhich panels is illustrated` in. Fig..-12.. .The.separate motor switches I 3 0 have -their.. control f circuits running .tn-mugatheeable.;n.35 .to the. push .button control switches findicatedgeneral-ly aty I42,.,each

onf tracks Trl t2" .'by means Vof cables I |74 eX-tending .up thelwving tofsuitable.'mechanismsal I6 on each lWing;forumannal `operation of the, checkingk devices. As illustrated, one end of a cable l I4.is anchored at y:I I 81 on the 1checking device, `vextend- `:ing 'thence l@towardthe7 center of fthe 4Joottorny sec.- Vtionvand-.around theapulley-IZD and `then -back :over :theabottomsection .andlaround the pulley 5122;.;:whencew the-4 cable.f.extends. upwardly along zthe'wing through-the guides-I 2 4 .and .over pulley ,fI 2:6r :atqthe opera'tingfdevicev I I 6 on the wing: pleatfornfi I.8.' zF-romflthef pulley fl 26 ;thetcable `-extends downward; through :thefguides I 24 and taround pulley-fil 22:;and has-1 its Vend y ,anchored at I Y28 on fthextchocking device =I .I 0.v y Thus by. suitable` manipulation of 'the operating ydevicessl :l5 fronfrthe wing .fplatformethe ohoclging. device .l `l0 may be .2mm/edf;along.Y its-@track toward or-Jawayrom a faboatinsthe-fdry dochV .l x; Therfcontrolrmeans for.; the --greversiblef` motors :fora-driving'.cthemumps-34 `is @best .illustrated vin fthe r diagrammaticl rshowing of Figi s. 13.--

Each

.f'motor361liastaswitchpl30 operabletbetween open .andyfclosedz-s positions, yby'rmeans `ofl any electroiamagnetf |32; and the circuit |33 kltoall ofthe motors has,I a switch f I3 4-c perlable .between normal sclosed lor;forward.-run-ningvi positon. l and a. reverse .nposition by l means of electroemagnet .I3l.. .-v The .motor-lswitches A30 f preferahlygargerlocated on 'ftheiwi-ngs off f. the zdry .ldcickg near. theirrespective 'lmotors whilefzthei switch! I 34 rco-ntrolling. :the cir.-

.cuit;-to all .of :the-motorsfmayv either Ibe onv a 'wing ofithetdry idock,, illethgeI dock-fcontrolhouse..is :there allocated,` 4as .rnay.loethe .case .at times, vor.y Aon .the fpierat which the ,dry dock -is anchored,A such .as

in ;the terminalft pit =|.3.l. indcated. irrEg. 1. y. Themotors :i5/herein shgwharfe vfoin/titreeeplnase veneration; andethe circuit I 3i" t'l 1 us -is v .a .three- ..phase rcircuit of suitable voltagefandnapacttvnd f a green lightindicatesmotor. operationtandtwhen .control switch I 42. having ya push, .button .II 44 .for yeifecting. the lclosing .ofthemotorfcontrol switch :I 30 to cause the motor toirotate.;and.aseparate switch |42 also' ispprovidedzwith a .lightfl48,.the energization of: which iscontreHed by tauxiliary contactsl .15;02 of ,f the associated I.motorcentr-o1 switch. |30 and isgillumiinatedawhen .fthesflatter -switch is ci-,osed and-;.the motor isfconditioned `for operation.

Each `panel 4-hason it .theapushv button 4switches 'for the motors of `vits--.associated,wing. Inaddition, one of the panels, as the panel-l38,-. has v.a `push yhut-tonswitch.l5-2v. similar tothe switches 4412,.: for controlling theoperatingycoi-l- I.36 -ofathe .reversingffswitchandfha-aing.,one pushbuttonzI-SII a that operates; the l. reversing .switch4 1.34 vto reverse y. the Y current to- .the .motors and a second pushbut- :tony l I 56 that restores r the reversing, .switch to. rits .normal condition vfor.forward vrotationfof the mo.-

tors; GableA Iflficontains::gthe @electricalwiring which connects switchv |52. 4.withfthe reversing Aswitcl1-l34.. Said push button` switchyalsohas a .light 1.58,. controlled by ,auxiliary. contactsl L60 of the' revers-ing switch, to be. illuminatedwhenfthe 'reversing switch; is. closedfor .reverseroperation of the; pump v.fmotors.. .-Usually `.the ,light I 58..:wil1 be red while A.the light 4I 48 will begreen. l. Hence not l accompanied by. ,therV red light. indicates;A for.-

. ward rota-tion. and when-.themed.lightl alsoshows, indicates reversel rotation.` `Thus all ..motorscan be indiyiduauystartea andsmpped py .push .but-

. ton. .control and. all7 .motors collectively 1ere` vconditioned for forward or reverse Arotation Since ..the .motor control tis by push. .buttonsj nd hence by the finger tip. ,the .,individualf.; motors. can be controlledV veasily. .for Vlong orshort periods ofi opleration eachzindependently of .all others and. each can be startedtandcstopped easily asfoftenjas desired. vAlso, oneach -ofthe controlpanelsjare El"scles "1.75 singltheflevel of vwater in .the respective'` compartments .o'fwthe dry docl-r,A each panel carrying gauges associated with its respective wing and there being a gauge for each compartment. Each gauge is closelyassociated, as immediatelyiover,` the button switch for the motor of its com-A ter level gauges' |62 and` l64 can be of any suitable `construction `and those herein illustrated areof the type containing a liquid column that risesand falls in accordance with the pressure of air acting thereon entrapped in an open-bot` tomed bell 166 located in the bottom Dart of the associated compartment for a gauge 162,0and; connected to the gauge, by a small pipe or duct |68. All ducts of the `gauge of a wingare groupedin a bundle and conducted from the dock tothe controlihou'se and to the gauges. As the control panels for the `two wings` are closely associated togetherthe operator can knowat ally timesthe condition'in thetvarious compartments of the dry dock and can quickly start or stop aiyparticular pump whenever the occasion seems to require and reversetheroperation of all pumps. Also the operator at lthe control center by 'reason of its chosen location isin position tto observe the operations beingiperformed lupon the dry dock and can direct and guide these operationsl by means `of the Ausual speech-amplifying systemwhich is indicated generally at `I'll'l, Fig. `l1, there being one loud speaker` instrument ateachcorner ofthe dry dock, both forward and aft. i As illustratedin Fig. `2, and also inFig. 13; the electrical connections leading from the Ydry `dock to thecontrol center on the pier extend through the goose' neck devices `I12,1in Fig. 2, which can providethe necessary slackne'ss in "the wiring. represented bytli'e'ilooped portions in Fig. 13, to permit raising and lowering of the dry dock without putting harmful'stresses on the wiring conlnect'ions. From* the goose necks,` stationarily mounted on the, pier, the wiringmay go tothe terminal pit l3l whence the various circuits lead to the control `panels at the control c'enter;

*If the dock isfloating high and itis desired to manual valves.;` I 1 .pump motors stopped. Y ,i

of the dock without` the necessity `for `closingthe When the boat is in the dock, the pumps'are started in a direction to discharge water `from the dock; compartments :to float the dock andthe boatxand when the proper elevation is attained,`

with the dock i'loorusually above water, the gate valvesin the pump `conduits are closed and the In Fig. 3, the various waterlevels are indicated by dotted linesl the line `2?2'indicating the water level exteriorly of the dry dock when it is iioating` i light and l with no `water therein, and theuline `231i indicatingthe outside water level whenithe dockfis elevatedwith aboat supported on` `the dock.f`-The upper" line 23S` indicates the exterior level of water when the ldry dockis submerged.`

4 According tothe presentinvention after `the i dock? is pumped free of .water and isvthus elevated with the boat thereon it is not necessary to close The operator at the control center can constantly observe `thecondition` within` each of `the come partments by meansl of thef gauge. indicators` vonv the control panel, andcanystart and stopor` reverse motorsselectively'tonattain desired rei f sults as regards level: ofthedry dock as a, whole or to permit water to enter certain compartments tohelp 'stabilize the dock 'structure-as determined bydistribution of weight in the boat. ".Also, the

operatorcan continually be aware of the .level of wateriexteriorlyof thev dryl dock and by this means determine whether the .dock isvhorizontal or `tilted either foreor aft Iand `can make needed submerge it to receive a boat the ood valves are opened tolet "in the outside water` by gravity. The pumps can also be operated to pump in water.

With a steel do'ckl or a" wooden one `heavily bal- `lastedby solidballast,when` the dockhas sunk suflicientlyto receive the boat, the outside water level may still be belowvthe water `level inthe dock` compartments when the flood valves are closed." `Withkthe wooden dock `of the present invention, however, when'the water levels inside and outside thefdock are about the same, and it is f desiredto furthensubmerge the dock, the flood gate ivalves are closedand the pumps started to raise thewaterylevel in the wings to sink the dock to the required level at which time `the pumps are stopped, and the butterfly valves close and the gate valves in the pump lines can be closed. `The docking of theboat is not a long operation,1howev ever, 4and vthe rate ordeakage of waterfrom the d ock through thebutteriiy valves is negligible and hence it is not essential to close the gatevalves in" thepump conduits. `If there is successive change of water level for any reason, as is made known to the dock operator by his water level indicators, he can start up the pumps `of those compartments that indicate a low waterlevel, to

raise` the level', thus jockeying the pumps to maintain the required submergence and balance adjustment of waterlevels in the compartments to bringthe dock back to a level condition: Also,

fromhis position `in the control station, `the i operator is able to observe the workmen onthe` dockand candirecttheirf labors Aover the amplifying` system and thus `utilize man power tolthe best possible advantage.' 'i i i' '1 i i Theuse of the reversibleeflow pumps thus'not only simplilies `and cheapens the pumping system by eliminating the `flow--direction` valves heretof. fore required with uni-dire'ctionalwflow` pumps,

but it alsoV permits aisinglel operative, falone,to control theraising and lowering ofthe dock."`

[The reversible-how` pump also permitslthe gravitational ooding ofthe dock compartments and, withfa woodendock, ltheir partial evacua,`

tion, `without the' use or presenceof theiiood gate, bythe flow of water" through the` pump since lwater can flow freely bygravity there-` through,` particularly when `the stresses dueto reversely driving the water-rotatedA impeller -are `not harmful `or when the reversedriv'e energy is )not suddenly applied full force. For this purpose the"butterfly valve can be omitted or' blocked open. For the usual conditions of dock operation, however, I prefer the useof `the butterfly valveasabove -described. i M

I claim: i Y gl. A boat dry-docking `system comprising a l floating" dry dock `having a plurality of independent buoyancyfregulating compartments, means `including reversible-flow pumps for `discharging water into and from said compartments, reversi-` ble electric ,motorswdriving said pumps, a `control and stopping of each pump individually and selectivelyiand :meansftat said stationialso controlling the direction of rotation of saimotorsfandz ingnand stoppingroeaohvpumpand means at said.'

station falso'l controllingithe fdirectionnof rotation ofsaidimotors' and'fpumpslcol-lectively; y

. 3. In a oatingv dryf'dooktiiavingfaplurality .of buoyancyaregulatingtfcompartments; Va `conduit conneoting eac'hfcompartmentrwith `the body'of piu-mp1: in :each compartment; a.; reversible driving motorffor '-each'vlspump-,f means ffor starting and stopping i' each pump independently of `all the otherpumpsa andmeans forreversing the direction ofA rotation ofiall lpumpsfconuointly.I

'4. fIn= a :floating dryy .'d'ockfhaving fall plurality e of buoyancy-regulating, `1 c'ompartrnents,l a f conduit connecting teach VYcompartment v`withwthe fbodyf of water in vwhiclrst-lie docksfdioatsgxa reversiblefow pumpin each @compartimenti a reversible driv-l ing motor, for each: pump,;f2means.for starting and stopping reach zpumpz" independentlyof all :other putains;means;y for'freversi-ng" the direction .of -rotationao'f; all'.'pumpszconjointly; and-a' control centertzfsituatedlf: to 'overlookrfsaidz dry vdock: ihousing said i starting :tand A`stopping.' nneans .and 1 said re' versnganeans.: l

i5'. A boat :dry-docking system -zcomprising la floatingiidry: docle` havingfa:plurality-of' independ ent-11-lctuoyanoyi-i-'egulatingA compartments; .means includingureversibleflowi'pumps i-for discharging water into; andifromlsaidcompartments; revers-l ible electric motors#driving'fsaidpumps,` con-trol moana forfaeach-fmotorandcpumpiioy vwhich any pumpiand itsnmotorf-c'anzbe 'operatedrindependa eritly roftfal'l :otheripumpsrand: motors", and-means for conditioning al1 motors'ic'onij'ontly':for-rot tioneinxanyfselected.fone-f of `opposite directions# of rotationiev i 6; IIn aioatingfdrydock; :having: af plurality `of water1in-Which 'the doel:` ilo'ats; 2a. reversible?- flow duity arever'sible motorior'operating said pumpV to' -pas'siwateriselectivelyl in oppositedirections'fin saidixcon-duit, a;normaIlyLCIOsed` valvezinfsaid con:v duit-,1 andautomatic means. fonopeninglsaid valve. when saidpumpis operatedzinany'nneto-f' its twoA directions-underpower'ofrsaid'niotor'.

9; Ina' roating dry. .dock having. ar'sbuoyamcyr regulating compartment, a: conduit fori admitting Water into and discharging l Water vfrom saidfzeonie partment, a reversible-Iiovtcpropeller Apumpiirzcv said conduit, Va motor for driving fsaid'v pumpimopposite: directionsgla. normally. closedfvalve 1in isaid conduitfandimeans responsive4 to the 'power/mow tation'nof said propel-ler :pumpfin :eachy direction forf'eiecting. the opening'l ofi said valv.

10. Av `boat dry-docking. system-1:comprisingfa oating drydo'ckihaving aplurality of buoyancy-1 regulating compartments', reversible and'eversiV- ble-now. pumpsA associated vvithA 'said comparte ments foradmitting water into vand discharging waterfrom saidf compartments a .reversible-dri-v`` ing motor for each pump; ai motoricircuit common to saidl motors, startingand -stopping-fmeanscontrolling thefconnection of` each mot'orziridepencl ently-ofl all other l"motors Withfsaidn circuit,v means for yreversing the vpower 'flow 'inl "said circuit` to reverse confjointlythe direction of rotationof said pumps land `associated motorszwhen Athelatterare connected to said circuit,` a control. center over lookinglthe dock, controlv means iforfeachlfstarting-andv stopping means.` groupeddn iarranged orde'r at said center, :controlmeanslfor saidifre= versing means :associated with saidiirst control means at said centen.motorfoperating'indicating means-associated with its respectivefcontrol means; reverse-conditionwindicatingmeans: asso"a ciated `with said `reversing control means;l and fa waterelevel indicating' means responsive to the Waterl level'lin each.vcompartment:associatedwith A ment.

buoyancy-regulatingltcompartments,` a conduit connecting-each compartmentlwitn the ywater in 'said conduit foreachfcompartmeritya'valve*controlling water flowf'fthrough each conduit, an electricfmotor f'orf'operatingwsaidx pump selectively .fin oppositefdirectionsgfelectro-responsivermeans controlling saidl, valve, tacontrol -station remote from said-f: pumps'andi fvalves, landrlmeans at said sta-- -f'eictingf` thef openinguof 'the associated rvalve., l

'18: In sa. floating: :d1-yx dock-having fa buoyancyregulatingfcompartment; 'a -con'duit for admitting walten finto-vrandidisehargingzwater from :said roompaintment, la reversible-now ".pump': in. :said-con- .1-1. -fA :floating .dryA dockicompnsmg la: ahonow water .tight structure having 1its-interior:V divided 'into :a series .of approximatelywater-.tig1itcom partments; a separatesingleiconduit leading fnom the exterior-,totheinterioraofeach compartment; a reversible pump in` eachsaidfdonduitffor. pumping zwater into the -Icompartmentslfandfaiso-efor pumping water out ofthe compartments,;i=powet means l for reversibly 4 operating the-pumps, and

f a valvein eachff saidf conduit between-tha pump andthe l exterior of the compartmentfor 'contr-ohR lingv both' inow and outow througlrsaid rconduit and pump when the pumprisf not driven by -fsaicl powermeans, Yand f means responsive-`l to theoperation of said power means A:for openingfsa-id valve' when saidpower-` means is. op,eratingand ef fecting-thef closing A'of said vaIVeI'When the power means is not operating to 'drive the pumpV 12. A vfloating .dry'dock andfoperatingsystem therefor including a oatingdry dockhaving'l-.a bottom hollow sectioniand ahollowwing section rising 'vertically valov'e the. bottom. section i along each sidetthe'reof, vbulkheads dividing thewini teriorsof4 the bottom and lwing .sections -intoa series-.of Watercompartment-s., each compartment having `extent both'in the -fbottomsectionandtin a Wing section, a reversiblenpumpdn eacli'fsaid compartment havinglits ow :passage open atlone end into its 'compartment and-*fopen atil its other endto thefexterior ofthe dry dock, separatevdrivi ing 'means4 for eacl'ii pumplo'catedl exteriorly-onsa said-wingy section; .acontrol center, controlmeans extending from' -all lthegpumpfdriving means T--to saidfcontrol center and operablev` there to selec-.1

tively control the drive of all of the pumps, and means also at the control `center for indicating the level of water in each said compartment.

13. In a floating dry dock having a series of separable hollow dryl dock units secured together to provide a compositel dry dock, each said unit having interior bulkheads dividingits `interior into a plurality of water compartments, a reversible pump in each compartment of each unit, separate reversible driving means for each pump, a control center common to all dockunits, and coni trol connections from all of the driving means eX- tended between the doek units having connec y tions with said motor starting switch means, a 1. power circuit, power reversing switch means connecting said circuit connectors with said power circuit in two different ways to obtain r'otationof said motors all in one and selectively all in the .i opposite directions, control connections from said individual motorstarting switch means and from said power reversing means to said control cen-v ter, and separate means at said center forselec-` tively operating said connections to eiect control of the switch means connected therewith.

tendedbetween at least some dock units to said control center including meansthere for selectively controlling the operation and direction of operation of said pump driving means.

` 14. In a oating dry dock having a series of connected dock units each having a Water compartment, a reversible-flow pump in each said compartment having its ilow passage open at one `end into its compartment andopen at its other end to the exterior of the dry dock, a separate reversible electric driving motor for each pump located on the associated unit, motor starting `25 tions with its associated pump, a control center 'for all dock units, electric circuit connectors exswitch means on each dockunit having connec- 15. In a water ballast floating dry dock having `a plurality of buoyancy regulating compartments and a single conduit for each" compartment for inow of water tcand outilow of water `from each compartment, means in each said conduit for propelling Water in` either direction `therethrough selectively, means at a remote location for selectively starting, stopping and reversing said pro-` pelling means in the individual conduits thereby to control list and -trim independently of operaf tion of manual valves, and means for automatically conditioning a said conduit, prior to each Y reversal of `its propelling .means for minimizing the torque imposed upon the propelling means.` i JAMES STUARTCRANDALL. 

